The invention relates to a crossed-coil rotating-magnet measuring instrument.
Crossed-coil rotating-magnet measuring instruments have an approximately cylindrical core, developed as a winding form, on which a first and a second coil are wound crossed one over the other, the second coil being arranged in the region of the ends of the winding form over the first coil and thus having a greater height of winding than the latter, there being mounted in the core a rotating magnet whose pointer shaft is extended out of an extension on the core.
Such known cross-coil rotating-magnet measuring instruments are used for various measuring and indicating purposes, for instance for the measurement of the level of filling of containers or temperature or else as voltmeter or ammeter.
The known crossed-coil rotating-magnet measuring instruments have a core used as winding form and within which the rotating magnet is turnably mounted. From one end of the substantially cylindrical core there protrudes an extension within which the rotating-magnet shaft is arranged and passes into the pointer shaft which is extended out of the extension. Upon the winding of the core, the turns of the coils are deformed in the region of the extension of the core and thus do not lie in a flat rectangular winding plane. Since furthermore the two coils which cross each other on the core must necessarily be wound one above the other in the region of the ends of the core, the heights of winding of the two coils are different.
It has been found that with known crossed-coil rotating-magnet measuring instruments of the aforementioned type there can only be obtained angles of deflection which are slightly above 90.degree.. If only the first quadrant essentially is utilized in these measuring instruments, calibration to the desired final value of the full deflection can be effected by adjustment of at least one voltage signal which acts on one of the two coils. However, it is not readily possible to use such crossed-coil rotating-magnet measuring instruments for reading over several quadrants since a displacement of the final value in the first quadrant necessarily results in a displacement in opposite direction in the third quadrant.
It is an object of the invention so to improve a crossed-coil rotating-magnet measuring instrument of the aforementioned type that it can be used with sufficient accuracy for reading over several quadrants and in particular up to the third quadrant. Difficulties resulting from a calibration by means of adjustment of a voltage signal in a coil are to be avoided in this connection.